It is well recognized that in the United States asthma morbidity and mortality are increased in urban poor minority populations where increased exposures to outdoor and indoor particulate occur. The specific aim of this study to assess the interactions between expression of common polymorphisms related to airway inflammation and health effects associated with particulate exposures among children with asthma. The investigators hope to define the interaction between expression of these polymorphisms and biological and health effects associated with particulate in a cohort of urban-poor predominantly minority children with mild to severe asthma who attend the Kunsberg School on the campus of National Jewish Hospital. Forty-five children who are students at the Kunsberg School will be followed on a daily basis over 4 consecutive school years beginning October 2007. Urine leukotriene E4 levels will be collected from each child on 16 consecutive schooldays and exhaled nitric oxide will be sampled as a marker of airway inflammation. Hourly ambient fine particulate concentrations will be monitored and personal exposure monitoring of particulate will be performed. Children will be assessed for expression of the glutathione-s-transferase m-1 and the 5-lipoxygenase tandem repeat polymorphisms. As these children attend school daily, the Kunsberg School provides a unique population in which individual exposures and asthma severity indices can be measured daily while other potentially confounding triggers can be monitored concurrently. In this way the interaction between genetic variability and environmental exposures can be precisely measured in children with asthma.